Horizontal Directional Drill Pipe Drive Connection With Locking Feature

ABSTRACT

The present invention is directed to a spindle assembly for connecting a drill string to a rotational drive for use in a horizontal directional drilling operation. The assembly comprises a saver sub attached to the rotational drive, and a drive chuck for connection to the drill string. The drive chuck and saver sub form a torque-transmitting connection by engaging through a seat in the saver sub and an engagement point on the drive chuck. Dowel pins may be used to rotationally lock and provide the engagement between the saver sub and the drive chuck. A collar may thread to the saver sub and cause an interference fit by engaging the drive chuck at a shoulder.

FIELD

The present invention relates generally to connection mechanisms fortransferring torque to a drill string in horizontal directional drillingprocesses.

BACKGROUND

Horizontal boring machines are used to install utility services or otherproducts underground. Horizontal directional drilling eliminates surfacedisruption along the length of the project, except at the entry and exitpoints, and reduces the likelihood of damaging previously buriedproducts.

The boring operation is a process of using a boring machine to advance adrill string through the earth along a desired path. The boring machinegenerally comprises a frame, a drive system mounted on the frame andconnected to one end of the drill string, and a boring tool connected tothe other end of the drill string. The drive system provides thrust androtation needed to advance the drill string and the boring tool throughthe earth. The drill string is generally comprised of a plurality ofdrill pipe sections joined together at threaded connections. As thepilot bore operation proceeds, the drill string is lengthened byrepeatedly adding pipe sections to the drill string.

When the pilot bore operation is completed, the drill string is pulledback through the borehole during a backreaming operation, generally withthe utility line or product to be installed underground connected to theend of the drill string. During this backreaming operation, pipesections are removed from the drill string as the drill string getsshorter. Each time a pipe section is taken from the drill string. As isthe case with the addition of pipe sections to the drill string, theprocess is repetitive.

A “driver”, or “saver sub”, is used as a connection to transmit thetorque and thrust/pullback forces generated by the rotational drive ofan HDD machine to a drill string. The connection comes in contact withevery pipe involved with a boring operation during both boring andpull-back and thus encounters high rates of wear on the connectionsurfaces of the component. As such, it is beneficial to make the parteasily replaceable. Further, it is beneficial to limit the wear pointsof the saver sub such that it is easy to replace, without requiringexcessive labor to rebuild the saver sub.

SUMMARY

The present invention comprises a torque-transmitting assembly for usewith a rotational drive used in a horizontal directional drillingoperation. The assembly comprises a saver sub and a drive chuck. Thesaver sub is rotationally attached to the rotational drive and comprisesa seat and a threaded portion. The drive chuck comprises an engagementpoint to engage the seat and a connection member for attachment to thedrill string. The drive chuck and saver sub are rotationally locked.

In another embodiment of the invention, it is directed to atorque-transmitting assembly for use with a rotational drive used in ahorizontal directional drilling operation. The assembly comprises asaver sub, a drive chuck, and a collar. The saver sub is rotationallyattached to the rotational drive. The saver sub comprises a seat and athreaded portion. The drive chuck comprises a shoulder, an engagementpoint to engage the seat, and a connection member for attachment to thedrill string. The collar comprises a threaded portion and an internalshoulder. The internal shoulder contacts the shoulder of the drive chucksuch that threading the collar onto the saver sub rotationally locks thesaver sub to the drive chuck.

In another embodiment, the invention is directed to a spindle assemblyfor rotating a drill string. The spindle assembly comprises a saver sub,a drive chuck, and a collar. The drive chuck is engaged with the saversub in non-threaded torque-transmitting engagement. The collar isdisposed about both an outer surface of the saver sub and an outersurface of the drive chuck to secure the saver sub to the drive chuck.The collar is threaded on the saver sub.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an HDD machine and drill string for use withthe spindle assembly of the invention disclosed herein.

FIG. 2 is an exploded perspective view of component parts of a spindleassembly.

FIG. 3 is a sectional side view of the assembled spindle assembly ofFIG. 2.

FIG. 4 is a sectional exploded perspective view of a collar, a drivechuck, and a wrench for use with the spindle assembly of FIG. 2.

FIG. 5 is an exploded perspective view of an alternative embodiment of aspindle assembly.

FIG. 6 is a perspective view of the assembled spindle assembly of FIG.5.

FIG. 7 is a sectional side view of an alternative embodiment of aspindle assembly.

FIG. 8 is an exploded perspective view of an alternative embodiment of aspindle assembly.

DETAILED DESCRIPTION

The disclosed invention is directed to a torque-transmitting spindleassembly 10 for use in horizontal directional drilling operations forboring under a surface of the ground 11. With reference to FIG. 1, thespindle assembly 10 connects a rotational drive 12 of a horizontaldirectional drilling (HDD) apparatus 14 to a drill string 16. The drillstring 16 comprises a plurality of segments which meet at pipe joints15. The spindle assembly 10, when fully assembled as described in moredetail below, is replaceable when the repeated making up and breakingout sections of drill pipe causes wear. Rotation of the rotational drive12 causes the spindle assembly 10 to rotate, which transmits torque tothe drill string 16 when the HDD apparatus 14 is in operation. Thistorque can make up or break loose the drill string 16 during addition orremoval of individual pipe sections, or transmit thrust and rotationthrough the drill string to a downhole tool 17.

With reference to FIG. 2, the spindle assembly 10 comprises a saver sub18, a drive chuck 20, a plurality of dowel pins 21, and a collar 22. Thesaver sub 18 comprises a first end 24 and a second end 26. The first end24 is fixedly attached to the rotational drive 12 (FIG. 1). Theconnection may take place through a flange, a sliding spline connection,a welded connection, a frictional interference fit, or other suitablemethods of joining the rotational drive 12 to the saver sub 18. As shownin FIG. 2, the saver sub 18 comprises a spline connection. The secondend 26 comprises an opening 28, a threaded portion 30 o and a seat 32.The opening 28 may be formed such that the drive chuck 20 comes incontact with the inner wall of the saver sub 18, or may be clearance fitsuch that the saver sub and drive chuck do not contact one anotherwithin the opening. As shown, the seat 32 comprises a plurality ofcastellations 34 formed in the second end 26. The castellations 34 areconfigured to engage a torque-carrying feature to transmit torque fromthe HDD apparatus 14 (FIG. 1) to the drill string 16 (FIG. 1). As shownherein, the castellations 34 engage the plurality of dowel pins 21. Asshown, there are six dowel pins 21, though other numbers are possible.The castellations 34 may be formed with a tapered opening to ensure thatthe dowel pins 21 can slip easily in and out of position when thespindle assembly 10 is not assembled. As shown, the spindle assembly 10comprises six castellations 34 and dowel pins 21.

The drive chuck 20 comprises a first end 40, a second end 42, anengagement point 44, a plurality of depressions 46, and a shoulder 48.The first end 40 extends within the opening 28 of the saver sub 18. Thefirst end 40 may operate to transmit thrust between the saver sub 18 anddrive chuck 20, or may alternatively only seal the connection betweenthe saver sub and drive chuck. The second end 42 is a connection memberfor thrust and rotation-transmitting connection to a drill string (FIG.1). This connection at the second end 42 may be a threaded connection.The threaded connection of the second end 42 may be on the inside oroutside of the drive chuck 20. The engagement point 44 is adapted toengage the seat 32 of the saver sub 18 for transmission of rotationforces between the saver sub and the drive chuck 20. The engagementbetween the seat 32 and engagement point 44 also may transmit thrustbetween the drive chuck 20 and saver sub 18.

The plurality of depressions 46 provide a location for the dowel pins 21to be placed. The depressions 46 may be formed with a tapered opening toallow the dowel pins 21 to easily slip into and out of the depressions.Alternatively, the depressions 46 may have parallel walls to provide apress-fit connection when the spindle assembly 10 is assembled. Theengagement point 44 may be machined such that the engagement point onlyengages the seat 32 through the dowel pins 21. In this embodiment, nodirect connection between the seat 32 and engagement point 44 takesplace, and all the torque-transmission and thrust-transmission occursbetween the seat and the dowel pins 21 and the dowel pins and theengagement point. The depressions 46 may be evenly spaced or may beunevenly spaced to allow for “clocking” orientation between the saversub 18 and the drive chuck 20. The shoulder 48 comprises a section ofthe drive chuck 20 where the diameter of the drive chuck changes.Preferably, the shoulder 48 comprises a sloped surface for interactionwith internal features of the collar (FIG. 3).

The collar 22 comprises a first end 60 and a second end 62. The firstend interacts with the threaded portion 30 of the saver sub 18 to holdthe elements of the spindle assembly 10 together. One skilled in the artwill appreciate that the spindle assembly could transmit torque withoutthe use of the collar 22.

With reference now to FIG. 3, the spindle assembly 10 is shown formedtogether in cross-section. As shown, the dowel pins 21 are locatedwithin the depressions 46 of the drive chuck 20 and the castellations 34of the saver sub 18. The depressions 46 have a tapered bottom to alloweasy removal when the spindle assembly is disassembled. The collar 22further comprises an internal shoulder 64 and a threaded portion 66formed on its internal wall. The threaded portion 66 is located at thefirst end 60 of the collar 22 and interacts with the threaded portion 30of the saver sub 18 to attach the collar to the saver sub. When fullyformed, the internal shoulder 64 contacts the shoulder 48 of the drivechuck 20. This connection forces the engagement point 44 toward the seat32.

One skilled in the art will appreciate that an angle of contact betweenthe internal shoulder 64 and shoulder 48 may be set at acute angles, orangles below 45 degrees. This causes a radial component in the preloadforce between the collar 22 and the drive chuck 20 as the threadedsection 66 of the collar is tightened onto the threaded to portion 30 ofthe saver sub. Thus, during the assembly of the spindle assembly 10,some of the rotational energy used forces the diameter of the collar 22to expand and the diameter of the drive chuck 20 to contract. Thisreduces relative movement between the saver sub 18 and drive chuck 20and thus decreases wear on internal components of the spindle assembly10.

When fully formed, the spindle assembly 10 may comprise an internalchannel 70 located within the center of the saver sub 18 and drive chuck20. The internal channel 70 allows fluid to be transmitted from the HDDmachine (FIG. 1) to the drill string (FIG. 1). A seal 72 is locatedabout a periphery of the drive chuck 20 to prevent fluid from escapingat the connection of the drive chuck and saver sub 18. Alternatively,the seal could be placed within the opening 28 of the saver sub formating with the first end 40 of the drive chuck 20. As shown, the seal72 is an o-ring. Other elastomeric or face seal mechanisms may be usedto provide a leak free connection between the drive chuck 20 and thesaver sub 18.

With reference now to FIG. 4, the collar 22 and drive chuck 20 are shownin cross-section with a wrench 80. The wrench comprises a handle 82 anda locking feature 84. The handle 82 allows an operator to apply torqueand turn the wrench 80. The locking feature is adapted to mate with thesecond end 62 of the collar 22. The second end 62 and locking feature 84have a complementary polygonal profile. Thus, the wrench 80 may be usedto thread and unthread the collar 22 to the saver sub 18 (FIG. 3). Theoperator may either rotate the wrench 80, or the collar 22 may be heldin place by the wrench or a vise while the rotational drive 12 (FIG. 1)rotates the saver sub 18.

With reference to FIG. 5, the collar 22 may alternatively be attached tothe saver sub 18 using a plurality of bolts 90 o through a flange 92 inthe collar. The plurality of bolts apply a clamping load to the drivechuck 20 through its shoulder 48. The saver sub 18 comprises a pluralityof bolt holes 94 adapted to receive the bolts 9 o. This embodimenttransfers torque between the saver sub 18 and drive chuck 20 throughdowel pins 21 as described with reference to FIGS. 2 and 3.

When fully connected to the rotational drive 12 of the HDD machine 14,this embodiment of the spindle assembly 10 appears as shown in FIG. 6.The spindle assembly 10 is attached to the rotational drive 12 (FIG. 1)at the sub saver 18 through a flange connection. The collar 22 isconnected to the sub saver 18 through bolts 90 o. The drive chuck 20 isengaged by the collar 22 at its shoulder (FIG. 5) and is adapted forconnection to a drill string (not shown) at its second end 42.

Alternative embodiments of the spindle assembly 10 without the use ofdowel pins are disclosed herein. With reference to FIG. 7, the first end40 of the drive chuck 20 comprises an external threaded portion 100. Thesecond end 26 of the saver sub 18 comprises an internal threaded portion102 within the opening 28. The pitch of the internal threaded portion102 may be slightly different than the pitch of the threaded portion 30of the saver sub 18. Alternatively, the internal threaded portion mayallow for a “right-hand” thread while the threaded portion 30 is a“left-hand” thread, or vice versa. As such, the forces generated on theinternal threaded portion during make up and break out of the collar 22on the saver sub 18 would not unthread the drive chuck 20.

With reference to FIG. 8, another alternative embodiment of the spindleassembly 10 is shown. In this embodiment, the seat 32 of the saver sub18 comprises castellations 34. These castellations 34 are adapted todirectly engage complementary castellations 110 o of the engagementpoint 44 of the drive chuck 20. Torque transmission occurs directly onthe complementary castellations 34, 11 o. The castellations 34, 110 maybe machined or casted. As shown, the shoulder 48 of the drive chuck 20is perpendicular, rather than the angled surface of FIG. 3, but it willbe appreciated that these may alternatively be angled as discussedabove.

In operation, the spindle assembly 10 is assembled for use with HDDmachine 14. The saver sub 18 is fixed to the rotational drive 12 of theHDD machine. The dowel rods 21 are placed within the depressions 46 ofthe drive chuck 20. The drive chuck 20 is then placed into the saver sub18 such that the seat 32 is proximate the engagement point 44. As shownin FIG. 2, the saver sub 18 engages the drive chuck intorque-transmitting arrangement through the dowel rods 21. The collar 22is then placed around a perimeter of the drive chuck 20 and secured tothe saver sub 18 such that the spindle assembly is rotationally locked.The collar 22 may be tightened by using a wrench 80. Alternatively, thecollar 22 may be clamped by vice wrenches (not shown) of the HDD machine14, then tightened by rotating the rotational drive 12 of the HDDmachine 14 to tighten the collar on the saver sub 18. Sections of drillstring 16 may then be threaded onto the drive chuck 20 as the spindleassembly is used to make up or break out sections of drill string, andto transmit torque to a downhole tool 17 for use in HDD operations.

While the dowel rods 21 have been disclosed herein as seated indepressions 46 of the drive chuck 20 for interaction with castellationson the saver sub 18, it is anticipated that this may be reversed. Thedepressions may alternatively be placed on the saver sub 18 forinteraction with castellations on the drive chuck 20. In thisalternative arrangement, the components would still be constrained bythe tightening of the collar 22.

One skilled in the art will appreciate that the embodiments herein arenot limiting on the scope of this invention. Alternative mechanisms forlocking the spindle assembly 10 together such that torque is transmittedbetween the rotational drive 12 and drill string 16 are possible withslight variation. For example, the dowel rods 21 may be integrallyformed with the drive chuck 20. The dowel rods may be replaced with aring that interacts with the drive chuck 20 and saver sub 18 to transmittorque.

Further, the connection discussed herein could also be used to connectthe drill string 16 with a downhole tool or cutting apparatus (notshown) at a terminal end of the drill string.

The spindle assembly 10 disclosed may be modified for use with adual-member drill string 16, for torque transmission to the innermember, outer member, or both (not shown).

1. A torque-transmitting assembly comprising: a saver sub; a drivechuck; an internal locking mechanism that maintains the drive chuck andsaver sub in rotationally-fixed relationship; and a collar thatsurrounds at least a portion of the saver sub and drive chuck; whereinthe saver sub and the drive chuck are in torque-transmitting engagementonly at the internal locking mechanism and the collar.
 2. The assemblyof claim 1 wherein the internal locking mechanism comprises at least onedowel pin.
 3. The assembly of claim 2 wherein the drive chuck defines atleast one depression for placement of the at least one dowel pin.
 4. Theassembly of claim 2 wherein the internal locking mechanism comprises sixdowel pins.
 5. The assembly of claim 2 wherein the at least one dowelpin is characterized by a circular cross-section.
 6. The assembly ofclaim 1, the saver sub and the drive chuck each having a rim in which aplurality of concavities are formed.
 7. The assembly of claim 6 in whichthe plural concavities in one rim are alignable in one-to-oneface-to-face correspondence with the plural concavities in the otherrim.
 8. The assembly of claim 7 in which the internal locking mechanismcomprises a plurality of dowel pins positionable between the pluralconcavities of the saver sub and the plural concavities of the drivechuck.
 9. The assembly of claim 8 wherein each of the plural dowel pinsis radially removable from when the collar is disassembled from thedrive chuck and saver sub.
 10. A kit comprising: the assembly of claim8, wherein the collar has a polygonal external profile; and a wrenchconfigured to thread and unthread the collar to the saver sub; whereinthe wrench has a polygonal internal profile complementary to theexternal profile of the collar.
 11. A horizontal directional drill forrotating a drill string comprising: the assembly of claim 8; and arotational drive, operatively connected to the assembly such thatoperation of the rotational drive rotates the saver sub and the drivechuck.
 12. The assembly of claim 1 further comprising: a shoulderdisposed on the drive chuck; and an internal shoulder disposed withinthe collar; wherein the internal shoulder contacts the shoulder of thedrive chuck when the saver sub and the collar are attached.
 13. Theassembly of claim 12 wherein the saver sub and collar are attached in athreaded connection.
 14. The assembly of claim 1 wherein the drive chuckis attached to a dual-member pipe string.
 15. A horizontal directionaldrill for rotating a drill string comprising: the assembly of claim 1;and a rotational drive, operatively connected to the assembly such thatoperation of the rotational drive rotates the saver sub and drive chuck.16. The horizontal directional drill of claim 15 wherein the drive chuckis connected to a drill string such that operation of the rotationaldrive rotates the drill string.
 17. A kit comprising: the assembly ofclaim 1, wherein the collar has a polygonal external profile; and awrench configured to thread and unthread the collar to the saver sub;wherein the wrench has a polygonal internal profile complementary to theexternal profile of the collar.
 18. A method for securing a drive chuckand a saver sub, the saver sub and the drive chuck each having a rim inwhich a plurality of concavities are formed, the method comprising:placing a plurality of keys between the rim of the saver sub and the rimof the drive chuck such that each of the plurality of keys engages oneof the plurality of concavities; placing a collar about the rim of thesaver sub and the rim of the drive chuck to maintain them in coaxialrelationship.
 19. The method of claim 18 in which each concavity extendsbetween spaced boundaries on its rim and subtends an included angle ofless than 360 degrees.
 20. The method of claim 18 in which the pluralconcavities in one rim are alignable in one-to-one face-to-facecorrespondence with the plural concavities in the other rim.
 21. Themethod of claim 18 further comprising threading the collar onto thesaver sub using a wrench.
 22. The method of claim 21 wherein the wrenchand the collar comprise complementary polygonal profiles.
 23. The methodof claim 18 wherein the plurality of keys each comprise a dowel pin. 24.The method of claim 18 wherein the collar maintains the rim of the saversub and the rim of the drive chuck in non-contacting relationship.